Piercing punch



R. A. GARGRAVE PIERCING PUNCH Dec. 212,` 1959 Filed NOV. 21, 195i:

PIERCING PUNCH ARobert A. Gai-grave, Dayton,- Ghio, assignoito ytonPerforators, Inc., Dayton, Ohio, a corporation of Ohio pplicationNovember 21, 1955, Serial No. 548,044 4 Claims. (Cl. :s3-12s) ing punchassemblies, whereby such assemblies may notv konly be economicallymanufactured, but will be more efficient and satisfactory in use,adaptable to aV wide yvariety of applications, and be unlikely to getout of repair.

. A further object of the invention is to obviate .the need for ageneral dismantling of the punch assembly, equipped with an ejectormechanism as described, in preparation forgrinding the work face.

Another object of the inventionl is to enable retraction of the ejectorpin in a punch assembly as described and the holding of the pin inretracted position without the necessity of gaining access to both endsof the punch element.

A further object of the invention is to enable the ejector pin to beground off in conjunction With'and to a corresponding extent as the workengaging face of the punch element.

A further object of the invention is to provide a piercing punchassembly possessing the advantageous struc- Fig. l is a view inlongitudinal section, partly diagrammatic, of a piercing punch assemblyin accordance with the illustrated embodiment of the invention;

Fig. 2 is a View of the punch element and holding means therefor, ofFig. 1, shown in larger scale and in position for grinding of the workengaging face;

Fig. 3 is a fragmentary view in longitudinal section l of the punchelement showing one location for a lateral opening in the punch element,forming a part of the instant invention; and

Fig. 4 is a view similar to Fig. 3 showing a different location for suchopening.

Like parts are indicated by similar characters of reference throughoutthe several views.

Referring to the drawings, a piercing punch assembly of a kind to whichthe instant invention may be applied comprises a punch holder and apunch pad 11 in parallel interconnected relation. In aligned spacedapart relation to the holder 10 and pad 11 is a die block 12 StatesPatent O receiving -an insert die 13 and backed up on its nnde'r side bya die holder 14. Disposed between the punch pad 11 and the die block 12is a stripper member 15, The pad 11 is provided with a bore 16 and acounterbore 17 receiving a punch element18, the latter having a barrelportion 19 fitting closely within the bore 15 and a head 21 received inthe counterbore 17 and limiting outward or -downward thrust of the punchelement relatively to the pad. The holder 10 backs up the pad 11 andprevents rearward withdrawing motion of the element 18.

The barrel 19 of the element 18 terminates in a reduced diameter portion22 axially aligned with an opening 23 in the stripper member 15 and withthe interior of die insert 13. According to the mode of operation ofassemblies of the kind described, a stock material 24 is fed across thedie block 12 while the separate assemblies iii-11 and 12J-14 reciprocaterelatively to one another. In response to suchmotion, the nose 22 of thepunch element 18- passes through the opening 23 in stripper plate 15 andengages the stock 24, continued approaching motion of the assemblies asdescribed resulting in a part of the stock being cut out of the materialthereofycorresponding in size to the interior of the die insert 13, theblank thus defined dropping downward through the insert 13 and out ofthe punch assembly by way of an opening 25 in the die holder 14. Thelower end of the nose portion 22 of the punch element may be consideredto define a work engaging surface or yface 26 and it Will be understoodthat for proper quality of work, this surface must be `kept planar andthe edges thereof kept sharp. It is necessary periodically to grind thework surface or face to maintain it in a good operating conditionagainst the effects of wear.

The punch element passes through the stock 24 in cut-- ting a blanktherefrom and on theretracting stroke of the punch element the strippermember or plate 15 is effective to restrain the stock from following thepunch element. It may occur that the cut blank, instead of dropping outof the assembly will tend to adhere to the work face 26 duringwithdrawal or retraction of the punch element. To obviate thisoccurrence, the `punch element is formed with a longitudinal throughbore 27 in which there is an ejector pin 28 adapted to extend throughand beyond the work face 26 to positively remove an adhering blanktherefrom.

The bore 27 terminates at its inner or upper end in a counterbore 29 inwhich is a head 31 integral with the pin 28. A compression spring 32also is in the counterbore 29, interposed between the head 31 and ascrew stud 33 installed in the outer end of the counterbore in the head21 of the punch element. The pin 28 is thrust downward or outward by thespring 32 and the parts are so proportioned that with the head 31 of thepin limiting in the bottom of counterbore 29 a predetermined part of thelength of the pin 28 projects through and beyond the face 26. The spring32 is relatively light and yields when the projecting part of the pin 28contacts the stock 24. By the reactant pressure of the stock 24,therefore, the pin 28 is retracted into the bore 27 during the downwardor cutting stroke of the punch so that the ejector pin is in effectmerely a part of the punch element. When the reactant pressure of thestock 24 is removed, however, after cutting of the blank therefrom, thespring 32 is released and thrusts the ejector pin 28 outward to theposition shown in Fig. l and any tendency of the blank to adhere to theface 26 accordingly is overcome.

The barrel 19 of the punch element 18 is formed, at the bottom ofcounterbore 28, with a lateral opening 34 in intersecting orcommunicating relation to the counterbore 29. VThe opening 34 ispredetermined in size to admit thereto a selective stop for the pin 28,as a cotter pin 35 as seen in Fig. 2. Thus, in aV nonoperating positionof the parts, the ejector pin 23 may be pressed by hand to a retractedposition as indicated in Fig. 2, and the cotter Apin 35 `or like deviceinserted. in the opening 34 in-positionl to underlie `the head 31 on theejector pin. yThe l ejector pin is by .this means locked in a retractedposition.

van insert member such as the cotter pin 35 will underlie the head ofthe ejector pin and lock it as described in retracted position.

The instant described construction and arrangement of parts makespossible grindingof the face 26 of the punch element without removal ofthe punch element from the pad 11 and holder 10. Thus, while the punchelement,

punch pad and punch holder are still assembled they may he inverted`from their normal working position and the work face 26 applied to thesurface of a grinding wheel or the like. The size of opening 34 or 36and of the sto-p member 35 to be inserted therein may in this connectionbe predetermined to define a retracted position for the ejector pinwhich places the outer end thereof in the plane of the face 26.Accordingly, as the face 26 is ground thel outer end of the pin 28 alsois ground and the same relative position of the parts at all times isin-this Way preserved.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is suscepti- 'ble of modification in its form, proportions,detail conthe appended claims.l

Having `thus `described my invention, I claim:

1. A piercing punch including a punch element having a working face anda longitudinal bore through said face, a counter bore aligned with saidbore through the end of the punch opposite said working face, a shoulderformed by said counter bore, a headed ejector pin received in said boreand said counterrbore with the head of the pin normally engaging saidshoulder, spring means urging said pin outwardly to-project'the outerend thereof from said bore through and beyond the. working faceofthepunch element, the. Workingface of thexpunch element and the face of theejector pin being both plane surfaces, said surfaces'being at rightanglesto the axisy of the bore within said punch element, an openingthrough the wall of said punch into said counter bore adjacent saidshoulder and means selectively installed in said opening for holdingsaid pin in a retracted position with the outer lend thereof invtheplane of said working `face on said 4punch element for unison grindingof said working Vface andv said pin.

, 2..Ther,structure according to claim 1. having means inserted in thecounter bore for adjusting the .tensioni on the springurging the pinoutwardly fromtheend of the vllv3; The .structure according to claim 1,,whereinthe :opening through the wallof the punch intersectstthe axis.ofithe counter. bore.

^ 4. 4The structure according to claim 1, v Whereinathe opening in thepunch is offset from the axis of the counfterlbore, andcsubstantiallytangent to the surfacefothe

